Pressure governor



April 23, 1929. F, H PARKE 1,709,871

PRESSURE GOVERNOR Filed Jan. 14, 1928 INVENTOR w .FREDERIC HPARKE a FBwww@ f ATTORNEY Patented Apr. 23, 1929.

UNITED STATES PATENT -oFFlcE.

FREDERIC H. PARKE, OF EDGEW'OOI), PENNSYLVANIA, ASSIGNOR TO THE WESTING-HOUSE AIR BRAKE COMPANY, OF WILMERDING, PENNSYLVANIA, A CORPORATION OFPENNSYLVAN PRESSURE GOVERNOR.

This invention relates to vehicles of vthe type in which an' internalcombustion or oil englne is employed for driving a generator forsupplying an electric current to the vehicle propelling motor and-fordriving a fluid compressor to supply fiuid under pressure to the fluidpressure brake system. In this type of vehicle, with the controller :forthe motor circuit in power on position, Athe 10 speed of the vehiclewdepends upon the speed ofthe engine, that is to say, if it is desiredto increase or decrease the speed of the vehicle, the speed of theengine will be inlcreased or decreased as the case may be, and Will thuseffect an increase or decrease in the supply of electric current fromthe generator to the vehicle propelling motor and the motor will operateto propel vthe vehicle in accordance with the'current supplied. v

When a vehicle,'equipped with my invention, is standing at a stop ordescending a grade, the engine continues to run at the usual slow idlingspeed, so that the rate at which fluid is compressed by the compressoris reduced below that obtained at the aver-v 'age running speed. Inorder 'to increase the output of the compressor I provide means forautomatically accelerating the engine and consequently the compressorunder conrent generated by the generator willl be of lowvoltage. Whenthe engine is accelerated E speed of the generator'is( correspondinglyincreased, with the result, that the current, generated b the generator,will be of high voltage, an if the motor circuit should be closed whilethe engine is running at increased speed and the controller in power onposition, this current would be suddenly imposed upon the propellingmotor, and due to its high voltage, mightv damage the motor to such anextent as to render it inoperative. E

To eli'ect the automatic opening and closing of the motor circuit, acontrol circuit of the usual type may be employed.

The principal object of my invention is to provide means automaticallyoperative for Application led January 14, 1928. Serial No. 246,875.

to a predetermined degree and the speed of Q the engine has `been reidlin speed.

A Iurther object of my invention vis to ro` vide .novel means forloading and unloa ing uced to substantially adequate supply of fluidunder pressure in the fluid pressure s stem at all times.

Other objects and,I

from the following more detailed -description.

In the accompanying drawing, the single figure is a diagrammatic view,principally in section, of a iluid compressing and electric circuitcontrol apparatus embodying my p invention. ditions where the engine isidling and the Athe high and low pressure cylinders of a fluidcompressor and for maintaining an advantages will appear In theaccompanying drawing, the reference character 1 indicates an internalcombustlon or 011 engine which may be mounted onv a vehicle in anydesired manner and drives an electric generator 2 for supplying currentto the vehicle` pro elllng motor 3 and also drives a two stage uidcompressor having a high pressure cylinder 4 and to increase the outputofthe compressor. the

a lowI pressurecylinder 5, the compressor piston (not shown) in the highpressure liuid under pressure to a storage or mam reservoir 9 through apipe 10, there being a check valve device 11 interposed in this pipe toprevent the back flow of fluid from the reservoir.

For the purpose of manually o erating `the usual throttle valve device,Wit which the engine may be equipped, a Athrottle operating lever 12 isprovided which is pivotally mounted, intermediate its ends, on a pivotpin 13 and is operatively connected with the throttle device of theengine, by a rod 14. For the purpose ot' automatically operating thethrottle device, a piston device 15 is provided which comprises acylinder 16 containing a piston 17 having a stem 18 which extendsthrough one end of the cylinder, and at its end is pivotally connectedwith one end of a lever 19 which is pivotally mounted on a pivot orulcrum pin 20. The other end of the lever 19 is pivotally and slidablyconnected with the rod 14 by a pin 21. l

Associated with the piston device l5 is a magnet valve device comprisinga magnet 22 adapted to control thev operation of double seat valves 23and `24. The valve 23 is contained in a valve chamber 25 which isconnected to the atmosphere by a passage 26 and the valve 24 iscontained in a valve chamber 27 which is connected with the reservoir 9by a pipe 28. Also contained in the valve chamber 27, is a coil spring29 which tends to maintain the valve 24 closed and the valve 23 open.Intermediate the valves 23 and 24 there is a chamber 30 which isconnected with the chamber 31 at one side ofthe piston 17, of the pistondevice 15, by a pipe 32.

A low pressure governor device 33 is provided, comprising a casingcontaining a cutout piston 34, subject to the pressure of a coil spring35, and carrying a valve 36, and also comprises a cut-in piston 37subject to the pressure of a coil spring 38 and carrying a valve 39.

Associated with the low pressure governor device 33, is an electricalswitchv device 40, comprising a casing having a chamber 41 containing apiston 42 which has a stem 43, the outer end of which projectsy throughthe casing, and has mounted thereon spaced contact members 44 and 45.The contact member 44 is adapted to be moved into and out of electricalengagement with contact terminals 46 and 47 of a motor control circuit,vand the contact member 45 is adapted to be moved into and out ofelectrical engagement with contact terminals 48 and 49 of a throttlecontrol circuit. The contact terminals 47 and 49 are connected togetherand to one terminal of a battery 50, or other desired source ofelectrical supply, by a wire 51. The other terminal of the battery 50 isconnected to a contact terminal 52 by a wire 53, and adjacent thiscontact terminal 52, there is a contact terminal 54'which is connectedwith one terminal of the magnet 22 by a wire 55, said Contact terminalsbeing adapted to be electrically connected byal Contact 56 carried bythe throttle lever 12, when said lever is in engine idling position asshown in the drawing. The other terminal of the magnet 22 is connectedto the i contact terminal 48 of the switch device 40, by a wire 57. Thecontact terminal 46 el the switch device 40 is connected by a wire 58with one terminal of the usual means (not shown) for effecting thecontrol of the motor circuit. From the Wire 53 there is a tap wire 59which is connected to the other terminal of the means for controllingthe motor circuit.

The motor circuit may comprise a wire 60 leading from one terminal ofthe generator to one terminal of the propelling motor 3, the otherterminal of the motor 3 and the other terminal of the generator beingconnected by wires 61 and62 respectively with the above mentionedcontrol means.

The purpose of the control means (not shown) is for automaticallyeii'ecting the control of the propelling motor circuit and is interposedbetween the control circuit wires 58 and 59 and the motor circuitwires'61 and 62 and may be of the type usually employed in vehicleswhich are electrically propelled. As this type of means is well known inthe art, vand as the details thereof do not enter into this invention,said means have not been shown nor have they been described in detail.

It will here be noted that if desired the switch device 40 may bearranged to directly control the propelling motor` circuit.

A high pressure governor 63 is also provided comprising a casingcontaining a cutout piston 64 subject to the pressure of a coil spring65 and carrying a valve 66, and also comprises a cut-in piston 67subject to the pressure of a coil spring 68 and carrying a valve 69. y

Associated with the high pressure governor device 3, is a valve device70, comprising a casing having a piston chamber 71 connected to a`passage 72 in the governor device 63 by a pipe 78 and containing apiston 74 having a stem 75, carrying a valve 76 which-is contained in avalve chamber 77, connected to the compressor cylinder 5, by the pipe10. Intermediate the piston 74 and valve 76 there is a chamber 79 whichis adapted to be connected to the atmosphere through a pipe 80 andpassage 81 in a valve device 82, there being a valve 83 contained in thecasing adapted to control the How of iuid from the low pressure cylinder5 of the compressor, to the atmosphere. The valve 83 has a stem 84 whichis secured to a piston 85, the chamber 86, atone side of which isconnected to a pipe 87 which is connected to a chamber 88 at one side ofa piston 89 contained in the casing of a piston valve device90. Thechamber 91' at the other side of the piston 89 is connected to the pipe7 leading from the high pressure cylinder 4 of the compressor to thereservoir 6. The piston 89 carries a valve pressure from the lowpressure cylinder 5, to the high pressure cylinder 4 of the compresser,a valve device 93 is provided, comprising a casing having a valvechamber 94 connected, by thepipe 10, to the low pressure cylinder 5,intermediate the cylinder and the check valve device 11, and containsavalve 95 adapted to control communication between the chamber 94 and achamber 96, which latter chamber is connected to the high pressurecylinder 4 by a pipe 97. The valve 95 has a stem to which is secured apiston 98, the chamber 99, at one side thereof, is connected to the,pipe87.

For the purpose pf controlling the unloading of the high pressurecylinder 4, a valve device 100 is provided which may be of substantiallythe same construction as the valve device 82. In this case, the valve 83cputrols communication from pipe 7, leading from the high pressurecylinder 4 of the compressor to the reservoir 6 and .piston chamber 91of the valve device 90, to the atmosphere through passage 81. 1t willhere be noted that the pipe 87 vconnects the chamber 99 of the valvedevice 93 and chambers 86 and 86 of the valve devices 82 and 100respectively with chamber 88 of the valve device 90.

With the main reservoir 9 charged with fluid under pressure exceeding apredetermined degree, the cut-in valve 69 will be maintained in its openposition, permitting the How ofduid at main reservoir pressure frompassage 101, past the valve 69 and through passage 72 and pipe 78 to thetace et piston 74, so that said piston is operated to hold the valve 76open.

The other parts of the equipment will be in the positions shown in thedrawing, so that if the engine 1 is running, luid discharged from thehighl pressure cylinder 4 will low to the atmosphere throughvpipe 7 andpassage 81' in, the valve device100 past the open valve 83. Between thevalve device 93 and the high pressure cylinder 4 of the compressorlthere is connected to the pipe 97, a relief valve device 102 which,when the valve 95 is seated, is operative to permit air to low from theatmosphere to the pipe 97, thereby preventing a vacuum from beingcreated in the pipe 97, by the action et the usual compressing piston ofthe high pressure cylinder 4. Fluid discharged from the low pressurecylinder 5 of the compressor will flow to the atmosphere through pipe10, valve chamber 77 of the valve device 70, past the open valve 76 intochamber 79 and from thence through pipe 80 and passage 81 and past theopen valve 83 of the valve device 82.

Should the pressure of fluid in the main.

reservoir 9 be decreased below that of theadjustment of the spring 68 ofthe high pressure governor device 63, the pressure of the spring actingon the cut-in piston 67 causes it to move down, seating the valve 69,and unseating a valve 103 carried by the piston 67, so that the supplyof fluid under pressure from the reservoir 9 to the valve device 70 iscut oft' and fluid under pressure in the piston chamber 71 of the valvedevice 70 is vented to the atmosphere by way of pipe 7 8, passage 72 inthe high pressure governor device 63, past the open valve 103 into aspring chamber l104 and through an atmospheric passage 105. rllhe valve76. of the valve device 70 is now caused to close by the pressure of aspring 106 contained in the piston chamber 77, thus preventing furtherflow of. fluid from the low pressure cylinder to the atmosphere, so thatfluid compressed in the low pressure cylinder will be supplied to themain reservoir 9. When the pressure of fluid in the reservoir 9 isincreased above that of the pressure of the spring 68, the pressure offluid, acting on the piston 67, causes it to move upwardly, unseatingthe valve 69, so that fluid under pressure will flow from the' reservoir9 to the' piston chamber 71 of the valve device 70, by

way of pipe 28, passage 101, past the open 9 valve 69, passage 72 andpipe 78, flow ont Huid from the passage 72 to the atmosphere p being cutell' by the seating of the valve 103 carried by the piston 67. Fluidunder pressure thus supplied to the chamber 71 of the valve device 70,causes the piston 74 to move downwardly against the pressure of thespring 106, which causes' the valve 76 to be unseated. Fluid dischargedfrom. the low pressure cylinder 5 now tlows to the atmosphere throughpipe 10, vvalve chamber 77, past the open valve 76 into chamber 79, andfrom thence through pipe 80, and passage 81 in the valve device 82, thusunloading the lovv pressure cylinder 5. 'llhe valve 83 of the valvedevice 82 is maintained open when the reservoir 6 is charged to apredetermined degree.

Should the engine 1 be running at idling speed, as when the vehicle isstanding at a stop or is descending a grade, and should the pressure ofduid in the reservoir 9 reduce at a faster rate than Huid under pressureis supplied by the low pressure cylinder 5 when the engine is runningatidling speed, the pressure of the fluid in the reservoir 9 may reduceto a degree which is lower than that necessary to maintain the cut-invalve 39 ol the low pressure governor device `33 open against thepressure el the coil spring 38 acting on the piston 37. When thepressure in the reservoir 9 is thus reduced to a predetermined degree,the pressure of the spring l38 causes the piston 37 to move downwardly,seating the cut-in valve 39 so as to cut off the further supply of fluidunder pressure to the piston chamber 41 of the switch device 40 by wayof pipe 28, passage 107 of the low pressure governor device 33 and achoked passage 108. As the valve 39 seats, a valve 109, carried by thepiston 37,unseats, and fluid under pressure in the piston chamber 41 ofthe switch device is vented to the atmosphere, through a passage .110,spring chamber 111 and atmospheric port 112, all of which are in the lowpressure governor device 33. The pressure of a spring 113 of the switchdevice, acting on the piston 42 f moves it downwardly, which firstcauses the contact 44 to be moved out of contact with the contactterminals 46 and 47, thus rendering the controlcircuit inoperative, sothat the motor circuit cannot beclosed. After the control-circuit isthus opened, the contact 45, carried by the stem 43, contacts with thecontact terminals 48 and 49. l/Vith the throttle lever 12 in engineidling position, as shown in the drawing, the contact 56 on the lever,connects the contact terminals 52 and 54, so that when the contactconnects the contact terminals 48 and 49, the throttle circuit will becompleted and the electric current flowing therethrough from the battery50, energizes the magnet 22, causing valve 23 of the magnet valve deviceto be seated, and the valve 24 to be unseated, and fluid under pressurein the valve chamber 27, supplied by the reservoir 9 through pipe 28,will How past the open valve 24 into chamber 30 and from thence to thepiston chamber 31 of the piston device 15. The pressure of fluidsupplied to the chamber 31, causes the piston 17 and stem 18 to moveforward, thus rotating the lever 19 about its pivot or fulcrum 20, and

duc to the connection between the lever and -the operating rod 14, therod will be moved in the direction of the arrowl in the drawing, causingthe usual throttle device of the engine 1 to be operated to acceleratethe engine.

As the engine`is thus accelerated to increase the output of the lowpressure cylinder 5 in order that the pressure of fluid in the reservoir9 may be built up rapidly, the speed of the generator 2 iscorrespondingly increased, resulting in the generation of an electriccurrent of high voltage, which, due to the control circuit being open,cannot be suddenly imposed upon the vehicle propelling motor 3. lf thecontrol circuit could be operated to close the ymotor circuit when theengine is accelerated, the high voltage current generated by thegenerator, would be suddenly imposed upon the motor 3, and wouldprobably damage said motor to such an extent as to render itinoperative.

With the engine 1 accelerated, the low pressure cylinder 5 compressesfluid into the reservoir 9 a great deal faster than when the engine isrunning at idling speed, and when the pressure of fluid in the reservoiris increased t-o a degree which is higher than the setting of the lowpressure governor device 33, said device will operate in the usualmanner so that the cut-in valve 39 will be unseated and fluid underpressure will flow from the reservoir 9 to the piston chamber 41 of theswitch device 40 by Way of pipe 28, passage 107 in the low pressuregovernor device 33, past the open cut-in valve 39 and through the chokedpassage 108. When the valve 39 is unseated, the valve 109, carried bythe cut--in piston 37, is seated, thus closing communication from thechamber 41 to the atmosphere through passage 110, chamber 111 andatmospher1c port 112. The choke' in the passage 108 is of such/'a 'sizethat lluid under pressure will flow slowly therethrough to the pistonchamber 41 so that the piston 42 which is subject to the pressure offluid in this chamber, will move slowly upward to the limit of itstravel. As the piston begins to be moved upwardly, the contact member 45carried by the stem 43 is moved out of engagement with the contactterminals 48 and 49, opening the throttle circuit, thus deenergizing themagnet 22, which permits the spring 29 to seat the valve 24 to cut offfurther supply of fluid under pressure to the piston chamber 31 of thepiston device 15, and unseat the valve 23 so that fluid under pressurein the piston chamber 31 will be vented to the atmosphere by way of pipe32, chamber 30 in the magnet valve device, past the open valve 23,through chamber 25 and atmospheric passage 26. When the chamber 31 isthus vented, the pressure of a spring 114, contained in the cylinder 1G,causes the piston 17 and stem 18 to move toward the right, rotating thelever 19 about its pivot 20 which permits the operating rod- 14 to movein the direction opposite that indicated by the arrow, operating thethrottle device to decelerate the engine. After the throttle device hasthus been operated, the speed of the engine 1 will gradually reduce toidling speed over a period of substantially thirtyfive to forty-fiveseconds, and I desire to delay the closing of the control circuit by thecontact member 44 for substantially7 the same length of time. Toaccomplish this, the opening through the choke in the passage 108 is ofsuch a size that fluid under pressure flows therethrough to the pistonchamber 41 of the switch device 40 at such a rate that the piston 42will move upwardly for a period of time substantially equal to the timeit requires to reduce the speed of the engine to idling speed. Afterthis time has elapsed, the contact 44 carried by the stem 43 of thevalve 42, will contact with the con- -tact terminals 46 and 47, thusclosing the control circuit, so that the operator now' has control ofthe motor circuit It will be understood that the time period interveningbetween the opening of the throttle circuit and the closing of thecontrol circuit may be greater-or less than that mentioned, and this maybe accomplished in a number of ways, some of which mayv be, the changingof the ssize of the opening in the choke in the passage 108, thechanging of the capacity of the spring 113, the changing of the travelof the piston, or the changing of the volume of the piston chamber 41Assuming the pressure of Huid in the high pressure reservoir 6 to bereduced to a predetermined. degree, fluid at main' reservoir pressureflowing through pipe 28, acting on the seated area of the vvalve 92 olthe valve device 90, together with the pressure of a spring 115, causesthe piston 89 to move u wardly, unseating the valve 92, so that duid atmain reservoir pressure liows into the chamber 88, and through pi es 87to the piston chambers 86 and 86 otP the valve devices82 and 100respectively and causes the pistons 85 and 85 to move downwardlyagainstthe action of springs 116 and llt and seating the valves 83 and 83. Atthe same time fluid under pressure dows'throuh pipe 87 into the pistonchamber 99 ot te valve device 93 and moves the piston 98 downwardlyagainst the action'ol a spring 117, unseating the valve 95, thusestablishing communication between the low pressure cylinder 5 and thehigh pressure cylinder 4l by way of pipes 10 and 97. As the valve 83 otthe valve device 82 is closed, lluid discharged trom the low pressurecylinder 5 cannot flow to the atmosphere through this valvedevice, butwill dow through pipe l0, valve device 93 and pipe 97 to the highpressure cylinder l, where it is further compressed and, as the valve83" of the valve device 100 is closed, the duid compressed will llowthrough pipe fl and check valve dcvice 8 into the reservoir 6. When'thepressure of the fluid in the reservoir 8 is again increased to apredetermined degree, the

pressure of the tllgd in the chamber 9i or3 the valve device 90, causesthe piston 89 to move downwardly, seating the valve 92, thus cutting odthe further supply of duid under pressure from the main reservoir 9 tothe piston chambers 88 and 86 of the valve devices 82 and l0()respectively and to the piston chamber 99 of the valve device 93. Fluidunder pressure in these three piston chambers is now vented tol theatmosphere through pipes 87, chamber 88 of the valve device 90 andatmospheric passage 1l8, thus permitting the springs 118 and 118P of thevalve devices 82 and 100 to move the pistons 85 and 85 upwardly tounseat the valves 83 and 83. At the same time,the pressure of the spring117 ofthe valve device`93 seats -the valve 95, thus cutting 0Hcommunication from the low pressure cylinder 5 to the high pressurecylinder t With the valve 83 of the valve device l0@ o en, the highpressure cilinderV d will unload to the atmosphere t rough pipe 7 andpassage 8l in the valve., With the valve 83 of the valve device 82 open,the low pressure cylinder 5 is adapted to be unloaded to the atmospherethrough passage 8l.

"-Yl'l, one illustrative embodiment ot the invention has been describedin detail, it is not my intention to limit its scope to that embodimentor otherwise than by the terms of the appended claims. s

Having now described my invention, what ll claim as new and desire tosecure by Letters Patent, is

lll'

l. The combination with an engine driven pressure of fluid compressed bythe compressor for automatically controlling the acceleration anddeceleration of the engine and for automatically edecting the control oisaid circuit according to the speed oi' the enme. g 2., 'lhe combinationwith an engine driven` compressor and electric generator and a circuitthrough which current generated by said generator may How, ot' meanssubject to the pressure ot duid compressed by the compressor forautomatically controlling the v acceleration and deceleration ot theengine and for rendering said circuit inoperative as said engine isautomatically accelerated.

3. 'lhe combination with anvengine driven compressor and electricgenerator and a circuit through which current generated by saidgenerator may dow, of means subject to the pressure of duid compressedby the compressor tor automatically controlling the acceleration anddeceleration oir' the engine and for rendering said circuit operativeairter said engine has been automatically decelerated to substantiallyidling speed.

4l. 'lhe combination with an engine driven compressor and electricgenerator and a circuit through which current generated by saidgenerator may dow, ot means automatically operated upon a predeterminedincrease in the pressure ot duid compressed by the compressor forcontrolling the ldeceleration or said engine and for rendering saidcircuit operative after the deceleration ot said engine.

5. The combination with an engine driven compressor and electricgenerator and a circuit through which current generated by saidgenerator may dow, of means subject to the pressure of duid compressedby the coinpressor for automatically controlling the acceleration anddeceleration of the engine and pressure sensitive means operativeautomatroe los

ically for rendering said circuit operative and inoperative only whenthe engine is operating at slow speed.

6. The combination with an engine driven compressor and electricgenerator, and a circuit through which current generated by thegenerator may flow, of an electric control circuit for controlling thegenerator circuit, an electric throttle circuit for controlling theacceleration and deceleration of the engine, and means subject to thepressure of fluid compressed by the compressor for con trolling theoperation of said control and throttle circuits.

7. rl`he combination with an engine driven compressor and electricgenerator, and a circuit through which current generated by thegenerator may flow, of' an electric control circuit for controlling thegeneiatoi circuit, an elect-ric throttle circuit for controlling theacceleration and deceleration of the engine, and means subject to thepressure of fluid compiessed by the compiessor for at one time renderingsaid control circuit operative and the throttle circuit inoperative andfor at another time rendering said control circuit inoperative and saidthrottle circuit operative.

8. The combination With an engine driven compressor and electricgenerator, and a circuit through which current generated by thegenerator may flow, of an electric control circuit for controlling thegenerator circuit, an electric throttle circuit for controlling theacceleration and deceleration of the engine, means subject to thepressure of fluid compressed by-the compressor for at one time renderingsaid control circuit operative and the throttle circuit inoperative andfor at another time rendering said control circuit inoperative and thethrottle circuit operative, and means for timing the action of the firstmentioned means.

9. The combination with an engine driven compressor and electricgenerator, and a circuit through Whicli current generated by thegenerator may flow, of an electric control circuit for controlling thegenerator circuit, an electric throttle circuit for controlling theacceleiation and deceleration of the engine, means subject to thepressure of fluid coinpressed by the compressor for at one timerendering said control circuit operative and the throttle circuitinoperative and for at another time rendering said control circuitinoperative and the throttle circuit operative, and means whereby a timeperiod is Caused to elapse between the opening of one of the lastmentioned circuits and the closing of the other.

10. The combinationy With an engine driven compressor and generator anda circuit through Which current generated by the generator may flow, ofpressure sensitive means for controlling thel acceleration anddeceleration of the engine, an electric throttle circuit for controllingthe operation of said pressure sensitive means, a circuit forcontrolling the generator circuit, and pressure sensitive meansoperative upon a predeteimined decrease in the pressure of fluidcompressed by the compressor for opening the control circuit to renderit inoperative and for closing the throttle eircuit to cause the firstmentioned pressure sensitive means to operate to accelerate the enginefrom idling speed, the second mentioned pressure sensitive means beingoperative upon a predetermined increase in the pressure of fluidcompressed by the compresser to open the throttle circuit to deceleratethe engine and to close the control circuit when the engine hasdecelerated to substantially idling speed.

11. rlhe combination With an engine driven compressor and generator' andan electric circuit through Which current generated by the generator mayflow, of a pressure sensitive element operative for controlling theacceleration and deceleration of the engine, a magnet valve device forcontrolling the pressure of fluid to said pressure sensitive means, anelectric circuit through which current is adapted to flow to operatesaid magnet valve device, and a switch device subject to fluidcompressed by the compressor fori` controlling both of said circuits.

12. rlhe combination with an enginev driven compressor and generator andan electric circuit through Which current generated by the generator mayflow, of a control circuit for controlling the generator circuit, apressure sensitive element operative for controlling the accelerationand deceleration of the engine, a magnet valve device for controllingthe pressure of fluid to said pressure sensitive means, an electricthrottle circuit through Which current may flow to operate said magnetvalve device, and a switch device subject to the pressure of fluid forcontrolling the control and throttle circuits.

13. rlhe combination With an engine driven compressor and generator anda circuit through which current generated by the generator may flow, ofa control circuit for effeet-ing the opening and closing of saidcircuit, means for automatically controlling the speed of the engine,and means subject to the pressure of f iuid compressed by the compressorfior opening and closing said control circuit only When the engine 1soperating at a slow speed. f

14. The combination With an engine driven compressor and generator and acircuit through which current generated `by the generator may flow, of acontrol circuit 'for effecting the opening and closingof said circuit,means for maintaining said control llO compressed by the compressor isabove av predetermined degree, for opening said control circuit When thepressure of fluid compressed by the compressor is below saidpredetermined degree and for effecting the acceleration of said engineto increase the supply of fluid under pressure from said compressor.

15. The combination with an engine driven compressor and` generator anda circuit through which current generated by the generator may flow, ofa control circuit for effecting the opening and closing of said circuit,means for accelerating and decelerating the engine, an electric throttlecircuit for controlling the operation of said means, pressure sensitivemeans for maintainin the control circuit open and the throttle circuitclosed when the pressure of fluid compressed by the compressor is belowapredetermined degree, and for opening said throttle circuit to effectthe deceleration of the engine When the fluid compressed by thecompressor has been increased to a predetermined degree, and means forcontrolling the operation of said pressure sensitive means so that ythecontrol circuity will be closed only after the pressure of fluidcompressed by the compressor has been increased to said predetermineddegree and the engine has been decelerated.

16. On a vehicle, the combination With an engine driven Huid compressorand an electric motor for driving the vehicle, of means forautomatically speeding up the engine and thereby the speed of thecompressor and means operated upon automatically' speeding up the enginefor preventing the supply of electric current to said motor.

In testimony whereof I have hereunto set my hand.

FREDERIC I-I. PARKE.

